"We are frequently asked the following question: Will the new emission standards now being imposed by Environmental Protection Agency (EPA) on methane and other volatile organics at the time of well completion help reduce the industry's greenhouse gas footprint in a meaningful way?

Our response is as follows: On the one hand, these new standards are an important step that will significantly reduce methane emissions, and therefore the greenhouse gas footprint of shale gas. Overall, according to the estimates of Howarth et al. (2011) and of EPA (2011), the regulations – if strictly enforced – will reduce total methane emissions from shale gas development by approximately one third (considering the entire life cycle, from well to final delivery of gas).

However, even with the regulations, the natural gas industry will remain the largest single source of methane pollution in the U.S., responsible for almost 40 percent of total human-controlled methane emissions, even with the new EPA regulations.

Even with the regulations, the greenhouse gas footprint of shale gas will remain larger than that of coal, when viewed over an integrated 20-year time period following emission to the atmosphere, because of the methane emissions (even though reduced).

Despite the new regulations, shale gas methane emissions will remain significant, with the estimates of EPA (2011) and Howarth et al. (2011) indicating a likely leakage of 2.5-3.9 percent of the amount of methane produced over the lifetime of a shale-gas well, and possibly as high as 6 percent. These ongoing emissions result from chronic leakages at the well site as well as chronic leakages and purposeful venting associated with gas storage, transmission through high-pressure pipeline, and distribution to consumers.

Given the limits of the control and the delayed start date, the EPA regulations on shale gas emissions must be considered to be too little, too late. The July 2011 United Nations report and the January 2012 paper by Shindell et al. in Science both stress the urgent need to reduce methane emissions globally, beginning immediately. Without stringent methane control, the global temperature is predicted to reach potentially dangerous levels – levels which may well lead to critical changes in the Earth's climate system such as huge increases in release of methane stored in arctic permafrost, leading to greatly accelerated global warming – within the next 15 to 40 years."

The above information is based on the background paper prepared by Robert Howarth (Cornell), Drew Shindell (NASA Goddard Space Inst.), Renee Santoro (Cornell), Anthony Ingraffea (Cornell), Nathan Phillips (Boston Univ.), and Amy Townsend-Small (Univ. of Cincinnati) for the US National Climate Assessment, and is based entirely on information in the peer-reviewed scientific literature. For more information, see: http://www.eeb.cornell.edu/howarth/Howarth%20et%20al.%20--%20National%20Climate%20Assessment.pdf.

ABOUT PSEThe nonprofit Physicians Scientists & Engineers for Healthy Energy (PSE) is dedicated to supplying vetted, evidence-based, scientific information and resources on unconventional gas development (high-volume hydrofracking) and other novel energy production methods. PSE's mission is to bring transparency to the important public policy issues surrounding such methods, helping to level the playing field for citizens, advocacy groups, media, policy-makers and politicians. For more information, go to http://www.PSEHealthyEnergy.org on the Web.